I don't understand this question, but we have to classify if each word-final -s or -er is not a suffix or if it is an inflectional or derivational suffix. I specifically don't understand the wording "word-final." I put that, for example, that in the word kiss, the "word-final -s" is not a suffix where-as the "word-final -s" in the word "brings" is an inflectional suffix. Is that correct? When is the word-final -s not inflectional if it is a suffix?